Polygonal Prisms Oscillating in Flow

We present the results of a series of experiments to investigate the response of different polygonal prisms placed in flow and allowed to oscillate in a direction perpendicular to the direction of incoming flow. Depending on their orientation with respect to the incoming flow, the polygonal prisms undergo Vortex-Induced Vibrations and in some cases also galloping as the reduced velocity is increased. Particle Image Velocimetry results show a variety of shedding patterns in the wake of the cylinder. Flow separation occurs at the sharp edges of the polygons, as expected, and the similarity of the wake patterns for different prisms is largely governed by the downstream orientation of the prisms. These experiments attempt to answer the question ‘how many sides does it take for a polygon to act as a cylinder when oscillating in flow?’